Reinforced concrete beams with web openings: A state of the art review

The construction of modern buildings requires many pipes and ducts in order to accommodate essential services such as air conditioning, electricity, telephone, and computer network. Web openings in concrete beams enable the installation of these services. A number of studies have been conducted with regards to reinforced concrete beams which contain web openings. The present paper aims to compile this state of the art work on the behaviour, analysis and design of Reinforced Concrete (RC) beams with transverse web openings. A variety of aspects will be highlighted and discussed including the classification of openings, guidelines for opening location, and the structural behaviour of RC beams with web openings. Various design approaches will also be detailed, for example the American Concrete Institute (ACI) approach, the Architectural Institute of Japan (AIJ) approach and the strut and tie method. Moreover, the strengthening of RC beams with openings using Fibre Reinforced Polymer (FRP) material and steel plates is presented. Finally, directions for future research based on the gaps which exist in the present work are presented.     

A state-of-the-art review on delayed ettringite attack on concrete

The paper presents a critical review of the sulphate attack related to ettringite formation. This process is associated with expansion. However, not necessarily any ettringite-related expansion is related to the sulphate attack. For example, early ettringite formation which occurs immediately (within hours) in a plastic fresh mixture does not produce any damaging expansion and is associated with the regulation of setting time of Portland cement paste. Expansion after the hardening of cement paste can be advantageously used for the development of chemical prestress in expansive cements. Delayed ettringite formation (DEF) occurs at late ages and the related heterogeneous expansion in a hardened concrete can produce cracking and spalling. Two different types of DEF are examined depending on the sulphate source: DEF caused by external sulphate attack or internal sulphate attack.     

Designing for creativity: A state of the art review

This review concerns itself with the so-called structured aids to creative behaviour. The published literature is outlined and shown to be extensive but fragmentary, diffuse and inconclusive. Four major families of techniques are discussed: brainstorming, synectics, morphological analysis and lateral thinking. Some less well known techniques are also considered briefly, and the problem of classification considered. There is little evidence of an accepted body of knowledge or paradigm, and the field contains contradictory results. It is argued that more attention needs to be directed towards understanding relationships between what the techniques are supposed to be doing on a theoretical level, and what they seem to be achieving in practice. Some fruitful areas for research and for practical actions are suggested, and an attempt has been made to summarize current views of practitioners that have not yet found widespread diffusion.     

Poly(3-hydroxyalkanoate)s: Diversification and biomedical applications: A state of the art review

Biomaterials have played an important role in the treatment of disease and the improvement of health care. Synthetic and naturally occurring biodegradable and biocompatible polymers have been used as biomaterials. Polyhydroxyalkanoates (PHAs) are promising materials for biomedical applications because they are biodegradable, non-toxic and biocompatible. We will shortly summarize the modification reactions, which include functionalization and grafting reactions, to improve the mechanical, thermal and hydrophilic properties of PHAs. The use of the modified PHAs in numerous biomedical applications, such as sutures, cardiovascular patches, wound dressings, scaffolds in tissue engineering, tissue repair/regeneration devices, drug carriers will be discussed in this review.     

Motorcycle helmets—A state of the art review

This paper tries to make an overview of the work carried out by scientific community in the area of road helmets safety. In an area that is constantly being pushed forward by market competition, self-awareness of danger and tighter standards, several research groups around the world have contributed to safety gear improvement.     

Simulation of safety: A review of the state of the art in road safety simulation modelling

Recent decades have seen considerable growth in computer capabilities, data collection technology and communication mediums. This growth has had considerable impact on our ability to replicate driver behaviour and understand the processes involved in failures in the traffic system. From time to time it is necessary to assess the level of development as a basis of determining how far we have come. This paper sets out to assess the state of the art in the use of computer models to simulate and assess the level of safety in existing and future traffic systems. It reviews developments in the area of road safety simulation models. In particular, it reviews computer models of driver and vehicle behaviour within a road context. It focuses on stochastic numerical models of traffic behaviour and how reliable these are in estimating levels of safety on the traffic network. Models of this type are commonly used in the assessment of traffic systems for capacity, delay and general performance. Adding safety to this assessment regime may allow more comprehensive assessment of future traffic systems. To date the models have focused primarily on vehicular traffic that is, cars and heavy vehicles. It has been shown that these models have potential in measuring the level of conflict on parts of the network and the measure of conflict correlated well with crash statistics. Interest in the prediction of crashes and crash severity is growing and new models are focusing on the continuum of general traffic conditions, conflict, severe conflict, crash and severe crashes. The paper also explores the general data types used to develop, calibrate and validate these models. Recent technological development in in-vehicle data collection, driver simulators and machine learning offers considerable potential for improving the behavioural base, rigour and application of road safety simulation models. The paper closes with some indication of areas of future development.     

Manufacturing perspective of enterprise application integration: the state of the art review

Manufacturing enterprise today has become a matter of effective and efficient application of information technology and knowledge-based engineering. Several new manufacturing paradigms such as virtual enterprise (or extended enterprise) and mass customization have resulted in a highly distributed and autonomous manufacturing system. On the one hand, this will increase the competitiveness of a firm in terms of quickly meeting dynamic changes in the market; on the other hand, this will also increase the difficulty of integrating different information and knowledge systems residing in each member firm. This integration is also called enterprise application integration (EAI) (here the term application means information systems or software systems for supporting manufacturing or service activities). The methodology for EAI has been studied for at least a decade; but no satisfactory solution has been found from a practical viewpoint. EAI is becoming even more difficult due to the boom in various enterprise information and knowledge systems (and also to ever increasing competition in the technical software market). The study presented in this paper conducted a critical analysis of existing solutions to EAI. We consider EAI as having two generic issues: semantic integration and syntactic integration. The main problem of semantic integration reduces to the general problem of enterprise or business modelling. The main problem of syntactic integration reduces to the general problem of software architecture of enterprise applications which enables interoperability between any two EAs. While the first issue is studied in the manufacturing field, the second issue is studied in the computing engineering field. In this paper, both issues are put together under the context of EAI and studied. The result of the study, together with our experience with one Canadian manufacturing firm, has led to the identification of several issues to be addressed in the future. We also outline possible ways to approach these issues.     

Ontologies in the context of product lifecycle management: state of the art literature review

The use of ontologies in the context of product lifecycle management (PLM) is gaining importance and popularity, while at the same time it generates a lot of controversy in discussions within scientific and engineering communities. Yet, what is ontology? What challenges have been addressed so far? What role does ontology play? Do we really need ontology? These are the core questions this paper seeks to address. We propose to conduct a comprehensive study of the concept of Ontology firstly in its domain of origin, Philosophy, and secondly in information science. Based on the understanding of this concept and an in-depth analysis of the state of the art, seven key roles of ontology are defined. These roles serve as a framework describing the general state of research on the use of ontologies in the context of PLM.     

Uniaxial tension test for the determination of fracture parameters of concrete: state of the art

An overview is given of methods to determine the strength and fracture energy of concrete subjected to uniaxial tension. The test method is often erroneously--and persistently--referred to as the `direct tension test'. After a brief review of historical, mostly indirect methods, the paper focuses on more recent servo-controlled testing techniques. Assessment of effects like secondary bending, and rotation and/or translations of the loading platens, as well as size/scale effects and environmental effects on fracture seem important for a proper definition of tensile strength and fracture energy. Implications for modeling are debated. The methods can be transferred directly to studies of other quasi-brittle geo-materials like natural rocks, clay and ice, fired clay bricks, plaster and the like.     

A state of the art on ADC error compensation methods

Analog-to-digital converters (ADCs) are critical components of signal-processing systems. ADC errors can compromise the overall accuracy and the effectiveness of the whole system. This leads researchers to direct increasing attention to error correction topics. In this paper, some ADC error compensation methods are briefly introduced according to a classification criterion based on the main research trends.     

Precision viticulture: The state of the art

The growth and collection of grapes or Viticulture is essential for producing various consumer products. Herein, we identified patents registered in the viticulture and wine areas, extracted specific information such as the applicant, country of origin and patent classification and analyzed the collected data. The filing frequencies and maps according to country and applicant were generated. Our analysis revealed two large patent groups and demonstrated that China is the top patent-producing country, rapidly acquiring substantial viticulture-related intellectual property. This study provides insights into the state of the art in viticulture and could be also be used to evaluate other business sectors.     

Critical review of the state of the art in multi-material fabrication via directed energy deposition

Directed energy deposition (DED) is an additive manufacturing technique that employs laser melting to permit for the free form manufacturing of components from many input materials from powder or wire form of feedstock. The nature of DED processes and advancements thereof has led to research that has been aimed at leveraging this additive manufacturing technology for the fabrication of high-value metallic alloys in addition to the exploration of multi-material composites and components – many of which are only possible to produce via DED. Herein, a critical review of the present body of research regarding DED of multi-materials is presented. Assessed are the developing research trends, design methodologies, common issues and challenges, as well as identification of the areas where further research should be directed.     

Geopolymer technology: the current state of the art

A brief history and review of geopolymer technology is presented with the aim of introducing the technology and the vast categories of materials that may be synthesized by alkali-activation of aluminosilicates. The fundamental chemical and structural characteristics of geopolymers derived from metakaolin, fly ash and slag are explored in terms of the effects of raw material selection on the properties of geopolymer composites. It is shown that the raw materials and processing conditions are critical in determining the setting behavior, workability and chemical and physical properties of geopolymeric products. The structural and chemical characteristics that are common to all geopolymeric materials are presented, as well as those that are determined by the specific interactions occurring in different systems, providing the ability for tailored design of geopolymers to specific applications in terms of both technical and commercial requirements.     

Chloride attack of reinforced concrete: an overview

The mechanism of chloride-induced corrosion of steel embedded in concrete, the ingress of chlorides into the concrete, and the threshold chloride content for corrosion to occur are discussed. The binding of chloride ions by cement compounds and the associated effect of using different cements, both Portland and blended, as well as other factors influencing corrosion, are considered. Tests for the penetrability of concrete to chlorides are described. Finally, the prevention of corrosion is discussed.     

分离式Hopkinson杆实验技术在混凝土材料动态力学性质研究中的应用综述

针对大直径Hopkinson杆实验技术在混凝土类脆性材料动态力学特性研究中的广泛应用,综述常规分离式Hopkinson杆实验技术在混凝土材料动态力学性质研究中面临的挑战与存在的关键问题,分别总结混凝土材料动态压缩和拉伸力学性质测试中常用的Hopkinson杆实验技术,并指出其局限性和不足之处。     

Rheology, flow behaviour and heat transfer of ice slurries: a review of the state of the art

This paper reviews recent studies on rheology, flow behaviour and heat transfer of two-phase aqueous secondary refrigerants (ice slurries). The difficulties in measuring their rheological properties for which standard rheometers prove to be poorly adapted are analysed. Special attention is paid to “vane-in-cup” rheometers, which can make it possible to determine the yield stress. Pressure losses in cylindrical tubes have been measured by many authors. Even if the results generally agree with two-phase flow theory, divergences in sensitivity to the solid fraction can be observed. The stratification observed by some authors for small-Reynolds-number flows and its effects on the pressure drop are addressed. In a last part, information concerning numerical values of the heat transfer coefficient of ice slurries are summarized. Heat transfer coefficients depend on many parameters, but are largely influenced by the flow regime. A geometry of heat exchanger is then proposed, which has already been effective for single-phase flows, and which may enhance heat transfer in ice slurry flows.

Résumé

Cet article passe en revue des études récentes concernant la rhéologie, le comportement des écoulements et le transfert thermique des frigoporteurs diphasiques aqueux (coulis de glace). Les difficultés de mesure des propriétés rhéologiques, pour lesquelles des rhéomètres courants s'avèrent mal adaptés, sont analysées. Une attention particulière est portée sur les rhéomètres du type « vane-in-cup » qui permettent de déterminer la contrainte seuil d'un matériau. Les pertes de charge linéaires dans des canalisations cylindriques ont été mesurées par de nombreux auteurs. Même si les résultats sont genéralement conformes à la théorie des écoulements diphasiques, on peut observer des divergences quant à la sensibilité à la concentration en glace. La stratification, observée par quelques auteurs pour des écoulements à faible nombre de Reynolds, et ses effets sur la chute de pression sont étudiés. Dans une dernière partie, les valeurs numériques du coefficient de transfert thermique des coulis de glace sont récapitulées. Les coefficients de transfert thermique dépendent de nombreux paramètres, mais sont fortement influencés par le régime d'écoulement. Nous proposons enfin un type d'échangeur de chaleur, dont l'efficacité a déjà été remarquée pour des écoulements monophasiques, et il pourrait s'avérer tout à fait adapté à des écoulements de coulis de glace.     

The state of the art in publication counting

The proceedings of the ISSI conferences in Stockholm, 2005, and Madrid, 2007, contain 85 contributions based on publication counting. The methods used in these contributions have been analyzed. The counting methods used are stated explicitly in 26 contributions and can be derived implicitly from the discussion of methods in 10 contributions. In only five contributions, there is a justification for the choice of method. Only one contribution gives information about different results obtained by using different methods. The non-additive results from whole counting give problems in the calculation of shares in seven contributions, but these problems are not mentioned. Only 11 contributions give a term (terms) for the counting method(s) used. To illustrate the problems, 11 of the contributions are discussed in detail. The conclusion is that 40 years of publication counting have not resulted in general agreement on definitions of methods and terminology nor in any kind of standardization.